What is Feline Leukemia Virus (FeLV)?
What is it?
How is it Treated?
Breed Predispositions
No specific cat breeds are predisposed to feline leukemia virus (FeLV) infection. However, cats allowed to roam freely and have close contact with other cats, such as in multi-cat households, are at a higher risk of disease.
Introduction
Samantha had always been vigilant about her cat, Bella’s, health, ensuring she received regular check-ups and vaccinations. However, one day she noticed Bella was unusually lethargic, had lost weight, and was no longer grooming herself as she usually would. Concerned, Samantha took Bella to the veterinarian for a thorough examination. The diagnosis came as a devastating shock: Bella had leukemia.
Leukemia is a cancer that affects cats’ white blood cells. The disease causes these cells to grow abnormally and become too many or weak. This leads to problems with the cat’s immune system and may cause infections, organ failure, bleeding, and weight loss.
The infection is spread through saliva and urine and can live for months outside the body. Cats develop Leukemia when white blood cells called lymphocytes become cancerous. The most common type of Leukemia in cats is called Feline Leukemia Virus (FeLV). FeLV causes immune system problems, leading to infections, tumors, and organ failure.
According to the American Association of Feline Practitioners, the feline leukemia virus (FeLV) is the second leading cause of death, next only to trauma, and kills most cats who become persistently infected within three years of diagnosis.
Other types of Leukemia include Lymphocytic Leukemia and Myeloid Leukemia. These two types of Leukemia are rarer than FeLV.
Lymphocytic Leukemia occurs when lymphocytes grow out of control and begin dividing uncontrollably. This results in large numbers of abnormal lymphocytes clumping together in the bloodstream.
Myeloid Leukemia occurs when the bone marrow stops producing normal red blood cells, platelets, and white blood cells. Instead, these cells have too many immature versions of each cell type.
How Feline is Leukemia Virus Transmitted?
Feline Leukemia is a contagious disease that spreads quickly among cats. If an infected cat comes in close contact with healthy ones, the chances of contracting the disease increase.
Many cats can become infected with FeLV through blood transfusions, organ transplants, breeding, needle sharing, bite wounds, cat bites, and vertical transmission (from mother to offspring).
Cats can also catch the disease from one another through grooming, fighting, kissing, biting, licking, and sharing food bowls. They can also contract it from a sick cat or kitten.

Those cats who live together in close quarters are most at risk of contracting the virus. However, there are several ways to prevent infection. One is to keep your cat indoors. Another is to vaccinate your cat against FeLV.
However, even though exposure to the feline leukemia virus (FeLV) doesn’t necessarily mean that a cat will die from it, most cats exposed to FeLV will eventually succumb to the disease if they don’t get treatment.
Causes of Cat Leukemia
Cats are very susceptible to Leukemia because of their unique immune system. Their white blood cells cannot fight off cancerous and human white blood cells. This makes cats especially vulnerable to developing Leukemia.
There are many causes of Leukemia in cats. The most common cause is radiation exposure. Radiation affects DNA, which controls cell growth and division. Radiation exposure can lead to genetic mutations that may result in Leukemia.
Another possible cause of Leukemia in cats is the feline immunodeficiency virus (FIV). FIV is a retrovirus that infects the cat’s immune system. Like HIV, FIV weakens the body’s ability to fight infection.
Other factors contributing to Leukemia in cats include age, breed, diet, genetics, and stress.
What Disease Does the FeLV Cause?
FeLV is a virus that affects domestic cats. It causes lymphocytic Leukemia, a cancer of the blood cells. There are three types of feline Leukemia – acute, chronic, and immune-mediated. Acute Leukemia occurs within weeks or months of infection, while chronic Leukemia develops over several years. Immune-mediated Leukemia is caused by another viral infection called FIV (feline immunodeficiency virus).
“feline leukemia” is the most common virus among felines, especially domestic shorthairs. Domestic shorthairs are the most commonly owned cat breed in North America.
There are two types of feline Leukemia: Non-Hodgkin’s lymphoma (NHL) and Hodgkin’s lymphoma (HL). Both types of feline Leukemia can affect both males and females.
Feline Leukemia Symptoms
FeLV-positive cats do not continually develop symptoms; some remain healthy virus carriers. However, some cats will develop a life-threatening secondary disease called lymphosarcoma. They may become sick and die prematurely due to complications associated with their illness.
Here are five common symptoms of Leukemia in cats:
- Anemia
- Poor coat condition
- Lethargy
- Loss of appetite
- Vomiting
- Diarrhea
- Abdominal Pain
These symptoms are often accompanied by fever, increased thirst, and decreased activity levels.
As these symptoms progress, your cat may become increasingly weak and appear listless. They may also vomit frequently.
Affected cats may show signs such as enlarged lymph nodes, coughing, vomiting, diarrhea, bleeding under the skin, or even difficulty breathing.
If you think your pet might be sick, you must take them to the veterinarian immediately.
Diagnosis of Leukemia in Cats
Diagnosis of FeLV takes several tests to see if your cat has Feline Leukemia Virus (FeLV).
ELISA Test
The enzyme-linked immunosorbent assay test measures antibodies against the feline leukemia virus in the serum. This test is used to diagnose infection. A positive test indicates exposure to FeLV. An antibody titer greater than or equal to 1:80 is diagnostic for FeLV.
IFA Test
The indirect fluorescent antibody test detects the presence of specific antigens associated with FeLV. A positive test indicates active infection. An antigen titer greater than or equal to 1:160 is considered diagnostic for FeLV.
If you suspect your cat is infected with Feline Leukemia Virus, consult your veterinarian immediately. Your veterinarian will recommend treatment options based on the severity of symptoms and your cat’s overall health. Treatment includes medication and possibly chemotherapy.
Treatment for Leukemia in Felines
There are several ways to treat and help eliminate the virus in cats. One option is chemotherapy. Chemotherapy involves giving drugs intravenously through a needle inserted into a vein. Another option is radiation therapy. Radiation uses X-rays to kill cancer in cats.

Chemotherapy
Chemotherapy is used to kill cancer cells. It works best when given before tumors become too large. Chemotherapy drugs damage DNA inside mass tumor cells so they cannot grow and divide. As a result, they can cause side effects such as vomiting, diarrhea, hair loss, skin rashes, mouth sores, fever, fatigue, weight loss, and depression. Some cats recover from chemotherapy without any problems; others develop life-threatening complications.
If you decide to use chemotherapy, there are different treatment protocols. Some treatments involve multiple injections over weeks or months. Other treatments require only one injection.
Immunotherapy
Immunotherapy involves injecting a vaccine into the bloodstream. Vaccination stimulates the immune system to produce antibodies against specific diseases. For example, there is an effective vaccine for feline Leukemia, but it won’t 100% prevent infection. Therefore, it is not considered a core vaccination.
Radiation Therapy
Radiation therapy uses X-rays to destroy cancer cells. Radiation therapy is recommended after chemotherapy if the disease hasn’t been eliminated. This helps prevent the return of cancer cells. Side effects vary widely among individuals. Most cats tolerate radiation well. However, some cats get sick, lose their appetite, vomit, or suffer from diarrhea.
Radiation therapy works best when given before surgery or other invasive procedures. Therefore, it is usually given in combination with chemotherapy. The goal of radiation therapy is to destroy all cancerous cells.
In most cases, radiation therapy is combined with chemotherapy. However, if your cat has been diagnosed with non-Hodgkin’s lymphoma, it may receive radiation therapy alone.
Surgery
Another option for treating Leukemia in cats is surgery. Surgery removes affected organs or parts of the body. Sometimes, this includes removing the entire spleen. In addition, surgery is often done to remove tumors or diseased tissue. Cats undergoing surgery must stay under anesthesia for several hours. Afterward, they’ll need special care until they’re fully recovered.
Surgery may be necessary because chemotherapy alone isn’t effective at curing Leukemia. But surgery doesn’t cure Leukemia either. So, if you’re considering surgery, talk to your veterinarian about the risks versus benefits of surgery.
Hospice Care
Finally, there’s a third option for treating Leukemia in pets. This option is known as hospice care. Hospice care is similar to palliative care. Palliative care focuses on relieving pain and discomfort. Hospice care focuses on providing comfort during the last stages of life.
Hospice care usually begins once a cat reaches end-stage disease. End-stage disease means that a pet’s health is declining rapidly. At this point, the pet’s quality of life is poor.
During hospice care, veterinarians monitor the pet’s condition closely. They watch for signs of distress and pain. They also keep track of any side effects from medications.
How to Prevent Feline Leukemia Virus Infections?
The Centers for Disease Control and Prevention (CDC) recommends keeping cats indoors because they are susceptible to rabies. The CDC says that although most cats don’t bite people, they transmit diseases such as feline leukemia, feline immunodeficiency virus, toxoplasmosis, and ringworm.
The good news is that there is a cure for feline Leukemia, and owners can do everything possible to prevent the spreading of the infection. Here are some things you can do to avoid getting sick yourself.
- Keep Your Cat Away From Other Pets
Cats naturally live among themselves, but if you want to keep your cat healthy, you must separate him from other pets. This includes dogs, hamsters, birds, rabbits, guinea pigs, ferrets, and other cats. Ask your veterinarian for advice if you need help properly housebreaking a kitten.
- Don’t Let Them Eat Raw Meat
Raw meat is dangerous for cats because it contains germs like salmonella and E. coli. So you should never feed your cat raw meat, and you shouldn’t let her eat anything from someone else’s mouth. Instead, give her canned food, dry kibble, or frozen treats.
- Watch Out For Fleas And Ticks
Fleas and ticks are prevalent in the summertime. Fleas can bite your cat and then jump onto another animal. When they land on an unsuspecting cat, they can get stuck under his skin. This will lead to itching, scratching, and bleeding.
Ticks are more likely to infect your cat than fleas. These insects have long legs that can crawl up your cat’s body and attach to its fur. Once connected, they suck blood until they become engorged with blood. Then they drop off and wait for another victim.
- Make Sure To Get A Regular Checkup
Your vet should be able to tell if your cat has Leukemia just by looking at him. He might notice swollen lymph nodes, an enlarged spleen, or pale gums. If he does find something wrong, he may recommend further tests.
- Be Careful About Sharing Food Bowls
If you share food bowls with your cat, wash them thoroughly after every use. Also, keep all leftover food from lying around. It could attract mice and rats, which would harm your cat.
- Clean Up After Him
It would be best to regularly clean your cat’s litter box so that no dirt gets into his system. You can also wipe down his bedding and toys to remove any bacteria.
- Vaccinate Against FeLV
FeLV is not contagious in cats. But if you own multiple cats, you can protect them all from this deadly disease by giving each of them a vaccination.
- Monitor His Health
It would be best if you observed your cat for signs of illness. Then, contact your vet immediately if you see any unusual behavior, such as vomiting, diarrhea, lethargy, or weight loss.
Frequently Asked Questions
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